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Preserving highlights - stopping down/increase ASA

J

Justin Anderson

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I'm working as DIT on a red shoot this weekend and I'm looking for some good resources on this.

Do any of you ever shoot RED 1-2 stops under or at a higher ASA to preserve image highlights?

I've been wanting to test how this would look for a long time now, but this is the first time I've had the opportunity. Our tech scout is Thursday.

cheers,
-J
 
Hi,

Setting your lightmeter to 320 asa will do that to some extent in any case.

Stephen
 
Justin,

Yep, protect those highlights at all costs. Burn outs are the first giveaway you're shooting digital. Even if the aesthetic is to burn out highlights, leave that to post where it can be done more elegantly with adjustable curves - as long as your subject isn't being dug too deep into the noise floor.

I'm constantly stopping down my camera when working in uncontrolled situations such as bright clouds behind talent while shooting towards the sun. I bounce as much light in the actors' faces as they can stand without blinding them.

Of course, the key is controlling those ratios between highlights and shadow.

In controlled situations, I try to fix highlights on set - dulling spray, streaks and tips, practicals dimmed/reduced and supported by instruments outside the frame etc. - the usual stuff. If I can't, I lift the shadows with overall fills - big lights bounced off of big fabrics, walls, grip trucks, whatever will suffice.

And, the RED histograms and peak indicators are your best friend if you're not using a meter - and often when you are using a meter. I often switch between my chosen color space (REC709 for my recent feature) and RAW metering to see what is clipping in each situation. Additionally, I set my high zebras between 102 and 106. If I see zebras I know I'm near clipping but still safe. If zebras disappear in a highlight, I know I've clipped.

Michael
 
Great article about exposure method with Red in Creative Cow:

GO to: Creative Cow web site,
GO to : Tutorial
GO to Section (at your left): /tutorials/redcamera
Click on :Exposing the RED: Perfect Exposure, Every Time

Quotes from the article:

The reason for this is that the RAW image is linear (as opposed to film, which is logarithmic). This means that for Red, out of 4096 brightness values available, the brightest stop has 2048 values, the 2nd brightest stop has 1024 brightness values, the 3rd brightest stop has 512 brightness values, the 4th brightest stop has 256 brightness values, the 5th brightest stop has 128 brightness values and so on.

As you can see most of the brightness values are in the top 2 stops, so the more information you can capture there will give you the most detail and least amount of noise in your picture.”

Anyone at Red can confirm this ?

I usually rate 320 ASA in EXT/DAY and 200 ASA in low contrast or tungsten situation. Since the DOF is so short, its difficult to stay around 200 ASA and sometime got to use 320 ASA to give the 1st AC 2/3 stop and have more DOF.

Anyone know why ive post the link of this article and RedUser just show a different URL ?!

ex: http://library.creativecow.net/articles/battistella_david/RED_camera_Exposure.php
 
Etienne Caron said:
The reason for this is that the RAW image is linear (as opposed to film, which is logarithmic). This means that for Red, out of 4096 brightness values available, the brightest stop has 2048 values, the 2nd brightest stop has 1024 brightness values, the 3rd brightest stop has 512 brightness values, the 4th brightest stop has 256 brightness values, the 5th brightest stop has 128 brightness values and so on.

As you can see most of the brightness values are in the top 2 stops, so the more information you can capture there will give you the most detail and least amount of noise in your picture.”

Anyone at Red can confirm this ?
Click to expand...

Yeah, I'd love to know too.

Does this mean that the right 3/4 of the histogram are the best places to get a good image from?
 
“With Red and its' RAW image format the DSLR still photographer's approach is best. The most effective way to get the best picture when shooting a RAW image is to expose to the right. This means no matter what your final image will look like expose the shot so it's as close as comfortable to the right edge of the histogram. This gives the most detail and texture and least amount of noise to the picture no matter how dark the final image is."
"As you can see most of the brightness values are in the top 2 stops, so the more information you can capture there will give you the most detail and least amount of noise in your picture.”

I'm trying to understand what this means. Does this mean expose with the bulk of the information at the right of the histogram? Or does it mean expose, keeping the data close to the right of the histogram but not touching it?

I'm confused because in this picture example, the bulk of the image data is on the left of the histogram.
RGB__HISTOGRAM.jpg
 
So I'm guessing, in order for the histogram to be an accurate map of the data, I should be shooting in the most linear gamma and color space as possible, right?

Which setting should I chose to get that?
 
The Macgregor thread is here.

http://www.reduser.net/forum/showthread.php?t=12863

I contacted him for the article but I think he was not able to do the interview. ( a guy this talented must be very busy) His tests are an excellent example of exposure and RED RAW recording.

The main difference between RED and film is at the TOP end (as Ted Schilowitz of RED explains so well in the article) This is why it is important to expose as close to the right as you can (without clipping) so that you are recording the widest possible range of image data.

In our tests to 35mm film, when extracting r3d files in log space we found that this was particularly important and evident.

That said, the REDcode blows out much the same way film does, but you can't recover information in those areas the way yo could with film.

David
 
Michael Morlan said:
Justin,

Yep, protect those highlights at all costs. Burn outs are the first giveaway you're shooting digital. Even if the aesthetic is to burn out highlights, leave that to post where it can be done more elegantly with adjustable curves - as long as your subject isn't being dug too deep into the noise floor.

I'm constantly stopping down my camera when working in uncontrolled situations such as bright clouds behind talent while shooting towards the sun. I bounce as much light in the actors' faces as they can stand without blinding them.

Of course, the key is controlling those ratios between highlights and shadow.

In controlled situations, I try to fix highlights on set - dulling spray, streaks and tips, practicals dimmed/reduced and supported by instruments outside the frame etc. - the usual stuff. If I can't, I lift the shadows with overall fills - big lights bounced off of big fabrics, walls, grip trucks, whatever will suffice.

And, the RED histograms and peak indicators are your best friend if you're not using a meter - and often when you are using a meter. I often switch between my chosen color space (REC709 for my recent feature) and RAW metering to see what is clipping in each situation. Additionally, I set my high zebras between 102 and 106. If I see zebras I know I'm near clipping but still safe. If zebras disappear in a highlight, I know I've clipped.

Michael
Click to expand...

Thanks for all that. We'll be sure to test that.
 
IMO changing the ISO setting on the camera is essentially useless as it's in no way affecting the sensitivity of the sensor. All you're doing is applying a metadata exposure increase and, effectively, brightening the image on your monitor.

Whenever possible feed the RED enough light to get your histogram nice and fat from the lower midrange right up to the highlights without clipping. Watch your stoplights (though they trip at 1% of pixels in the given channel clipped, so in some ways the stoplights are too alarmist). Increasing the ISO on the camera is just fooling yourself into thinking you're getting more exposure, and you're going to wind up with noisier shadows than you already get.

To most accurately check your exposure, be sure to VIEW RAW when checking your lighting setups. Trust that more than the histogram you get in Redspace.
 
Exposing left is the single most common mistake I see that strips the raw image of it's wonderful potential. It is the hardest thing in the world to get DP's to agree to--and gaffers hate me. lol
 
Actually, QXZ, the "fat" area of a histogram can be anywhere depending on the nature of the scene. If your scene is a nighttime street with lots of shadows and bright highlights, then the "fat" will be to the left with a "thin" segment extending to the right. If the scene is a snowy day, then the "fat" will tend towards the right.

Definitely watch the traffic light and use your judgment when allowing some highlight burn and shadow crushing. It's all aesthetics.

Michael
 
Michael Morlan said:
Actually, QXZ, the "fat" area of a histogram can be anywhere depending on the nature of the scene. If your scene is a nighttime street with lots of shadows and bright highlights, then the "fat" will be to the left with a "thin" segment extending to the right. If the scene is a snowy day, then the "fat" will tend towards the right.

Definitely watch the traffic light and use your judgment when allowing some highlight burn and shadow crushing. It's all aesthetics.

Michael
Click to expand...

Great point Michael.

Let's not forget that the ASA rating will help you in terms of creating nice QT files. So it is not really just tricking the camera. IE: FOr shoots that are not going back to film adjusting ASA/ISO acts a bit like gain and allows for a nice range in the QT media.

Everything has it's place in this technology.

David
 
So I understand the left and rights but what about the peaks going up? What is that telling me? It seems the traffic lights turn on when one of the colors peak.
 
Spike said:
So I understand the left and rights but what about the peaks going up? What is that telling me? It seems the traffic lights turn on when one of the colors peak.
Click to expand...


The lights mean that you are blowing out pixels on the specific channel.

David
 
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